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"Norton, Mark"
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Plant drought survival under climate change and strategies to improve perennial grasses. A review
The three cool-season perennial forage grasses cocksfoot/orchardgrass,
Dactylis glomerata
L., tall fescue,
Festuca arundinacea
Schreb. syn.
Lolium arundinaceum
(Schreb.) Darbysh., and phalaris/harding grass,
Phalaris aquatica
L., are of major economic and ecological importance in regions with summer-dry environments. This review considers the constraints that these species are likely to experience under current and predicted increase of droughts due to climate change scenarios in south-eastern Australia, the southern Great Plains of USA and the Western Mediterranean Basin. The review identifies research required to maximise the development and use of C3 cool-season grasses with enhanced resilience to drought while considering the concern of some regulators that these grasses may be potential weeds. The state of knowledge of factors influencing plant drought survival and therefore recovery after stress and long-term persistence is discussed in the light of adaptive strategies. The major research needs identified to enhance traits conferring drought survival include (1) increasing the depth and density of grass root systems to strengthen dehydration avoidance; (2) exploring the biochemical, molecular and hydraulic bases of dehydration tolerance and improving techniques to measure this trait; (3) breaking the trade-off between summer dormancy and forage yield potential and improving understanding of environmental, biochemical and genetic controls over summer dormancy; (4) identifying non-toxic endophyte strains compatible with summer-dormant cultivars of tall fescue to enhance drought survival; and (5) enhancing seed production capability of new cultivars as well as the development of agronomic management packages for promoting stable mixtures combining perennial grasses and legumes. The weed potential of newly introduced summer-dormant cultivars is concluded to be minor. The research directions proposed here should improve pasture grass resilience and forage crop sustainability in Mediterranean and temperate summer-dry environments under the future drier and warmer conditions associated with climate change.
Journal Article
Novel use of a trabecular metal spacer in the treatment of a long-standing ulnar fracture non-union
The use of trabecular metal (TM) implants in spine and joint surgery is well documented. However, their use has yet to be reported as an alternative to either allograft or autograft in the management of fracture non-unions. We present our experience in using a TM implant for treating a patient with a long-standing ulnar fracture non-union. Excision of devitalised bone resulted in a 17 mm defect which the TM implant was used to infill. The defect was then bridged with a locking plate. At 2-year clinical and radiographic review, bony union and a pain-free return to full function was noted. In this case, the use of a TM implant avoided the morbidity associated with an iliac crest autograft.
Journal Article
Huntingtin Fragments and SOD1 Mutants Form Soluble Oligomers in the Cell
Diffusion coefficients of huntingtin (Htt) fragments and SOD1 mutants expressed in cells were measured using fluorescence correlation spectroscopy. The diffusion mobilities of both non-pathological Htt fragments (25 polyQs) and pathological Htt fragments (103 polyQs) were much slower than expected for monomers suggesting that they oligomerize. The mobility of these fragments was unaffected by duration of expression or by over-expression of Hsp70 and Hsp40. However in cells with HttQ103 inclusions, diffusion measurements showed that the residual cytosolic HttQ103 was monomeric. These results suggest that both non-pathological and pathological Htt fragments form soluble oligomers in the cytosol with the properties of the oligomers determining whether they cause pathology. SOD1 with point mutations (A4V, G37R, and G85R) also had slower diffusional mobility than the wild-type protein whose mobility was consistent with that of a dimer. However, the decrease in mobility of the different SOD1 mutants did not correlate with their known pathology. Therefore, while soluble oligomers always seem to be present under conditions where cell pathology occurs, the presence of the oligomers, in itself, does not determine the extent of neuropathology.
Journal Article
Identification and Measurement of Summer Dormancy in Temperate Perennial Grasses
There is an apparent increase in frequency of prolonged droughts in regions with Mediterranean climates. This has rekindled interest in the summer dormancy trait for improving drought resistance of temperate perennial pasture grasses. In orchardgrass (Dactylis glomerata L.), tall fescue [Lolium arundinaceum (Schreb.) Darbysh.], and phalaris (Phalaris aquatica L.), identification of the three common drought resistance traits of vascular plants, dehydration avoidance (or delay), dehydration tolerance, and summer dormancy, is often confused. Summer dormancy, the least common of these traits, is found in cool-season grasses from semiarid and arid Mediterranean climates and provides an enhanced level of drought resistance. It is best measured in field-grown plants previously exposed to low winter temperatures and short photoperiods. Those perennial grasses not exhibiting summer dormancy survive drought by avoiding and/or tolerating dehydration and express this as a response to water deficit irrespective of the season. Here we review three summer water-supply environments, full irrigation, midsummer storm, and summer drought, for their precision and repeatability in measuring dormancy. Full irrigation and midsummer storm can be recommended, but measurement of dormancy under prolonged drought caused inconsistencies.
Journal Article
Association between Environmental Factors and the Occurrence of Six Fumitory Species ('Fumaria' spp. L.) in Southern-Eastern Australia
The occurrence of Fumaria as a weed in south-eastern Australian cropping systems is believed to have increased substantially in recent decades. To study this, a survey was conducted in contrasting regions of this zone, viz. southern New South Wales, mid-north South Australia. The survey analysed the pattern of occurrence of each of the six naturalized species found (Fumaria bastardii, F. densiflora, F. muralis, F. officinalis, F. parviflora and F. capreolata) and the natural environmental factors associated with their distribution. While five species were primarily found in agricultural environments, F. capreolata occurred exclusively in non-agricultural situations characterized by the presence of high soil organic matter. F. densiflora and F. bastardii were the most widespread and abundant species. F. officinalis was the rarest.
Journal Article
Use radiography rarely, not routinely, for hip hemiarthroplasty
PurposeHip hemiarthroplasty (HA) is a commonly performed operation. A post-operative radiograph forms part of the routine hip fracture pathway, although patients are often mobilised prior to this investigation. This study seeks to provide evidence for a pragmatic clinical change to optimise patient safety and allocate limited resources within the National Health Service (NHS).MethodsWe undertook a retrospective database review of 1563 HA procedures to assess whether the routine ordering of check radiographs played an important role in a patient’s post-operative care.Results18 (1.2%) mechanical complications led to a return to theatre within 6 weeks of the index procedure. All were dislocations. Ten had a normal post-operative radiograph and five had documented suspicion of dislocation prior to radiography. The post-operative check radiograph was the sole identifier of dislocation in only three patients (0.2%). All three of these patients were pre-morbidly bed bound and non-communicative due to cognitive impairment (AMTS 0/10).ConclusionUnless a patient is pre-morbidly bed bound and cognitively impaired, routine post-operative radiography following HA surgery is of little clinical benefit, yet may carry considerable risk to the patient and cost to the NHS. A pragmatic compromise is to perform intra-operative fluoroscopic imaging.
Journal Article
Non-union following bilateral simultaneos Ganz trochanteric osteotomy
Between January 2003 and December 2004, 13 patients underwent bilateral resurfacing arthroplasty via a Ganz trochanteric osteotomy. This bilateral group was mobilised fully weight-bearing with crutches. During the same period 139 Ganz trochanteric osteotomies were performed for unilateral hip resurfacing. These patients were mobilised with crutches, weight-bearing up to 10 kg on the operated leg. Nine osteotomies (32%) in the bilateral group subsequently developed a symptomatic non-union requiring revision of fixation. This compares with 10 patients (7%) in the unilateral group. Applying the Fisher's exact test, the difference reached significance (P=0.0004). In two patients a second revision was required to achieve union. In one patient, revision of trochanteric fixation precipitated a deep infection. Protected weight-bearing following a Ganz trochanteric osteotomy is important to the success of the procedure. Simultaneous bilateral hip arthroplasty through a Ganz approach should be avoided. If it is undertaken, we recommend that patients should be non weight-bearing for 6 weeks following surgery. Non-union following a Ganz trochanteric osteotomy for arthroplasty carries a significant morbidity.
Journal Article